(a) Technical Field
The present invention relates to a novel process for preparing (+)-polyoxamic acid.
(b) Background Art
(+)-Polyoxamic acid, represented by Chemical Formula 1, is an amino acid that is comprised of five carbons that are all functionalized and possesses three contiguous stereogenic centers. Its chemical name is (2S,3S,4S)-2-amino-3,4,5-trihydroxypentanoic acid.

(+)-Polyoxamic acid is the key component of Polyoxins, natural peptidyl nucleoside antibiotics. Polyoxins were first isolated from Streptomyces cacoi var. aseonsis, and members of this family possess potent biological activities against the chitin synthetase of Candida albicans, a human fungal pathogen. So, they have been utilized as agricultural fungicides.
The first total synthesis of (+)-polyoxamic acid was reported in 1973 (H. Kuzuhara, H. Oruhi, S. Emoto. Agr. Biol. Che. 1973, 37, 949-951), and lots of methods for synthesizing this compound have been reported. A number of routes for the synthesis of this substance have been described, nearly all of which use chiral substances (e.g., carbohydrates) as starting materials (A. Tarrade, R. H. Dodd. J. Org. Chem. 2003, 68, 9521-9524). One exception to this general trend is found in the route for preparation of (+)-polyoxamic acid that utilizes an enantioselective phase-transfer conjugate addition reaction followed by an asymmetric dihydroxylation process (Y. Lee, H. G. Park. J. Org. Chem. 2011, 76, 740-743). So, almost all the synthetic routes that have been reported have limitation for preparation of the target compound in large quantity and with proper chirality.
The inventors of the present invention have developed an efficient and stereoselective route for the synthesis of (+)-polyoxamic acid, which begins with a commercially available chiral aziridine that until now has not been utilized as a starting material for the preparation of this target.